Such a machine tool is known already as having a support table mounting a workpiece and carrying a tool magazine from which necessary tools are taken out successively to effect various machinings in sequence. In the known machine tool of the kind described, as shown, for example, in the specification of U.S. Pat. No. 3,709,623, the tool magazine is placed at one end of the support table so as not to hinder the machining of the workpiece, so that the support table is made to travel a distance greater than the stroke necessary for the ordinary machining, when the tool is replaced. In consequence, the working space on the support table is undesirably limited by the installation of the tool magazine. The size of the support table also has to be increased to require larger sizes of devices such as bed, table feed device and so forth.